In computer network systems such as local-area networks (“LANs”), wide-area networks (“WANs”), and the Internet and the worldwide web (“WWW”) which operates thereon, email systems and associated protocols are often utilized to facilitate communication between two users of the network or email system. Each user has a unique network address which may be used for routing and identifying purposes in delivering an email message from one user (the “sender”) to another user (the “recipient”) on the network.
Email messages are typically sent from a sender to a recipient by the sender typing or otherwise preparing an email message on a PC (personal computer), which is itself typically coupled to a server coupled to a communications network such as the Internet. The email contains both a body or content portion, which contains the message itself, and the network email address(es) of the recipient(s). Email messages can also include more complex information such as attached files. In general, however, each email transmission from a sender to a recipient over a network includes some body or message portion and the network addresses of the sender and recipient. The email transmission may be referred to, in general, as an email message, which is transmitted via a network from a sender to a recipient.
The email message is thus transmitted from the sender PC to the local network router or server (e.g., an email server), which delivers the email message in packetized form to the network. The packets are each routed from one node of the network to another, in accordance with the recipient address information associated with the packets. These packets are received by a recipient server of the network, which can then assemble the received packets into the original email message and deliver the email message to the recipient's PC, which is attached to the recipient server. The email message may be routed through one or more routing servers between the sender's server and the recipient's server. These routing servers may be different types of servers provided by different vendors. The routing servers may queue and schedule the routing the email message according to its own schedule. As a result, the delivery of the email message may be delayed by the routing servers and such delays are sometimes unacceptable. In addition, such delay prevents the recipient from providing the sender an instant confirmation of arrival of the email message at the recipient, even if the sender enables a return receipt option on the outgoing email message.
For many users, the send and receive email server functions are performed by a service provider such as an Internet service provider (ISP). In order to receive email, a user must first “log in” to his ISP, typically by use of a modem and telephone line or other communications channel such as a cable system cable. Any email messages which have been received by the ISP for the user since the last time the user logged in to his ISP may then be delivered to the user-recipient. If the user keeps his PC continually logged on to his ISP and is present at his PC, he can receive email as soon as it is received by his ISP. The user's own PC may be configured to alert the user when it receives the email message from the ISP. However, many users log in only periodically to check for email messages. Thus, if an important email message arrives while the user is not logged in or is away from his PC terminal, the user will not be aware of this.